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Joint Committee on Environment, Transport, Culture and the Gaeltacht. WATER SUPPLY AND THE HYDROLOGICAL CYCLE : THE CASE IN IRELAND. WATER SUPPLY = PRIMARILY A HYDROLOGICAL PROBLEM. Paul Johnston & Laurence Gill, Civil and Environmental Engineering,
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Joint Committee on Environment, Transport, Culture and the Gaeltacht WATER SUPPLY AND THE HYDROLOGICAL CYCLE : THE CASE IN IRELAND WATER SUPPLY = PRIMARILY A HYDROLOGICAL PROBLEM Paul Johnston & Laurence Gill, Civil and Environmental Engineering, Trinity College Dublin October 2011
THE WATER SUPPLY PROBLEM IN IRELAND :TOO MUCH WATER IN THE WRONG PLACE (AT THE WRONG TIME)?
RAINFALL IS THE PRIMARY SOURCE OF WATER SUPPLY (MET EIREANN)
THE WATER BALANCE IN IRELAND : RAINFALL – EVAPOTRANSPIRATION (300mm to 1000mm per year) Source : Mills, Irish Geography, 2000
LONG TERM RAINFALL RECORDS SHOW TRENDS PARTICULARLY SINCE 1975 (Met Eireann)
WATER SUPPLY STRATEGY • Ireland has plenty of water, even increasing • ‘Shortages’ are due to increasing demand in centres that do not coincide with the areas of surplus water supply • Hydrological conditions in Ireland mean that water/rainfall moves through the system relatively quickly : residence times in surface and groundwater are short. • Access to the needed water can be a mix of surface and groundwater : but they are interconnected and one is not necessarily an alternative to the other. • The proposed Shannon abstraction is equivalent to approximately 28mm of net rainfall per year over the catchment, ie about 6% of the annual total • Water management must be holistic with a view to related ecological requirements
National Groundwater Recharge map 2009 Groundwater abstractions
INTER CATCHMENT WATER TRANSFER IS FEASIBLE BUT TAKING INTO ACCOUNT THE RISKS
WATER MANAGEMENT IN IRELAND • Water, unlike oil, is not consumed : it is the truly renewable resource • ‘Wastewater’ is effectively returned to the hydrological cycle • Thus, water management must be holistic, as envisaged by EU legislation, involving the whole hydrological cycle • Spatial variability in rainfall and hydrological conditions mean that water needs to be managed nationally (or regionally) to be effective. • Conservation and innovative methods of water harvesting and wastewater disposal have an important role but need to be managed consistently. • Care must be taken to separate the roles of regulation and protection from those of water supply and treatment/disposal. • Consolidate the disparate roles of several state agencies in water management
NATIONAL GROUNDWATER MONITORING NETWORK (EPA 2008) MONITORING IS A NATIONAL TASK : SHOULD BE UNDERTAKEN BY ONE AGENCY/ORGANIZATION